At Foro Italico however, Djokovic needed just 70 minutes to rally from an early break to beat qualifier Montanes 6-2 6-3.

The six-time grand slam winner says the display is a step on the road to performing at this month's French Open as well as at Wimbledon in June.

"It was a good performance, even though I know I can do better," Djokovic, who has reached the Rome final four times in the last five years, told reporters.

"I know my game has to be better in order to win my next challenge. But I'm heading in a good way because I didn't have a great week in Madrid and didn't have much practice.

"I came here very early; from Wednesday I spent a lot of hours on the court working hard, trying to prepare myself for what's coming up this week and also after the tournament in Rome -- two Grand Slams in less than a month's time.

Federer, whose return to action in Madrid after a two-month break ended with a third-round loss to Japan's Kei Nishikori, also eased through to the third round after beating Italian wild card Potito Starace 6-1 6-2.

Meanwhile, Serena Williams gained some family revenge when beating Laura Robson, who knocked sister Venus out in the first round, in straight sets.

The world number one's comfortable day against the rising Briton was in stark contrast to many of her seeded colleagues, three of whom crashed out on Tuesday.

Poland's fourth seed Agnieszka Radwanska was the highest to fall, losing 6-7 6-1 6-2 to Simona Halep of Romania in the second round, but she may have gained some consolation by seeing sister Urszula inflict defeat on 15th seed Ana Ivanovic.

Tenth seed Caroline Wozniacki of Denmark also failed in her bid to reach the second round, as the former world number one let slip a 5-2 lead against 48th-ranked Bojana Jovanovski in a third set tiebreak.

The girlfriend of golfer Rory McIlroy has struggled on clay this season, exiting in the first round in both Spain and Germany over the last month, and now succumbing at the first hurdle once again.

Jovanovski, 21, ended a poor run of form as the Serb claimed her first victory since the Australian Open in January.

2011 Wimbledon winner Petra Kvitova became the first woman into the third round as she beat Germany's Sabine Lisicki in another match that went to three sets.